The 2017 nominations form is at:
http://www.improbable.com/projects/surveys/arisia2017.html
Discussion of the Ig Nobels and the nominations is over at the "Fans of Arisia" page (https://www.facebook.com/groups/arisiafans/)
Information and history about the the Improbable awards is on their blog: http://www.improbable.com/